1. Field of the Invention
The present invention relates to a pipe for conveying solids provided at least at one end thereof with a circumferential radially extending coupling flange and an axially extending annular portion connected to the coupling flange, wherein an annular insert of a material having a greater resistance to wear as compared to the material of the pipe is arranged in a chamber formed by the coupling flange and the annular portion.
2. Description of the Related Art
Pipes for conveying solids, particularly concrete, are subjected to significant wear because of the abrasive effect of the conveyed medium. Because of turbulence at the radial offsets of two pipes coupled to each other, a wear which is higher than proportional occurs especially at the end at the inlet side of a pipe. The conveyed medium impinges against the end face portions of the pipe arranged downstream in the conveying direction.
Because of this increased wear, the ends of a pipe were provided with inserts of a material having a greater resistance to wear as compared to the pipe material. The purpose was to prevent premature wear of the pipe ends which could have rendered the entire pipe useless. These inserts, for example, in the form of wear rings, usually are of a non-weldable material. Therefore, it was not possible to weld the inserts to the ends of the pipes. For this reason, chambers were provided at the ends of the pipes in which the inserts were secured in their position.
DE 38 14 034 A1 discloses a curved cast pipe as a component of a pipe line for conveying solids in which inner wear inserts are provided at the ends of the cast pipe extending in radial planes of the radial flanges. The wear inserts can be pressed into corresponding recesses of the curved cast pipe or may be exchangeably mounted in these recesses. The manufacture of these recesses is comparatively simple in cast pipes because they can already be taken into consideration when the pipe is cast.
For reasons of weight, elongated pipes are usually not manufactured of cast iron, but of steel. Cylindrical steel pipes are manufactured essentially endless and are then cut to length as required for the specific application and are provided at the ends thereof with coupling flanges to be able to connect the pipes with each other. A receiving means for accommodating an insert can be provided in the coupling flanges. The coupling flanges are generally welded to the cylindrical steel pipe.
This configuration has the disadvantage that the area of the welding seam between the coupling flange and the steel pipe may become brittle which negatively influences the strength of the connection. Moreover, the coupling flanges are relatively expensive because they must be processed in a chip-producing manner for being able to meet their optimum function, i.e., an exact seat on the steel pipe and a precise positional orientation of the insert. Further costs are incurred by welding the coupling flange to the steel pipe.
As the cost for manufacturing a coupling flange and for the connection of the flange to the steel pipe increase, the costs of the individual pipe also increases. Additional cost factors are such measures as hardening the inner side of the steel pipe or constructing the steel pipe in two layers. In addition to high initial investment costs, the costs for replacement parts, for example, when a worn pipe has to be exchanged, are also high. Accordingly, there is a great potential for manufacturing such pipes more economically.